Nigeria head vows to find pirates

The delta region is notorious for the kidnapping of foreign oil workers

Nigeria's president has vowed to hunt down the pirates who attacked a number of oil workers and their military escort in the oil-rich delta region.

Olusegun Obasanjo instructed security forces to arrest the men.

The US oil firm Chevron Texaco says the number killed in Friday's attack has risen to seven - including two American oil contractors.

They were among nine people travelling on a boat along the Benin river, west of Warri, when they came under attack.

Presidential spokesman Remi Oyo said Mr Obasanjo is determined to "hunt down the perpetrators of this really dastardly crime".

The Delta state government has offered a $75,000 reward for information leading to the capture of the pirates.

In a statement the US embassy in the capital, Abuja, urged the government to "ensure that those responsible are brought to justice".

Plans 'on hold'

Kidnappings and ambushes are common in the Delta, which remains poor despite producing the bulk of Nigeria's oil wealth, says the BBC's Anna Borzello.

But this is believed to be the first time expatriates have been killed in an attack.

Militants opened fire on the boat in the swamps, west of the oil producing town of Warri late on Friday afternoon.

The team had been returning from work reopening oil wells that were closed down by an armed ethnic uprising in the area last year.

The US oil giant said its plans to reopen the oil wells were now on hold.

A Delta state government official told the BBC that representatives of Chevron, the state and the military will meet in Warri on Monday to discuss ways of improving security in the region.